Injection molding of cable ties

Description

BACKGROUND OF THE INVENTION

[0001] The present invention generally pertains to injection molding a tie that is useful for forming a loop for retaining a bundle of elongated articles, such as cables, and is particularly directed to injection molding a particular design of such a tie. According to such particular design. the tie includes an elongated tongue with two ends and two broad sides, a locking head at one end of the tongue, a tip at the other end of the tongue, a first set of ratchet teeth extending along one broad side of the tongue and a second set of ratchet teeth extending along the other broad side of the tongue; wherein the locking head has sides defining an opening for receiving the tip of the tongue to form said loop, including a movable pawl that is hinged at one side of said opening and with an abutment surface on the opposite side of said opening from the pawl; wherein the pawl has at least one pawl tooth disposed for engaging the first set of ratchet teeth when the tip of the tongue has been inserted through said opening with the second set of ratchet teeth facing the abutment surface, wherein the pawl. when the at least one pawl tooth is so engaged, is movable toward the abutment surface in response to pressure applied to the tongue in a direction opposite to the direction of said insertion in order to force the second set of ratchet teeth against the abutment surface; and at least one stationary tooth disposed on the abutment surface and having an apex for engaging the second set of ratchet teeth when the second set of ratchet teeth is forced against the abutment surface to thereby in combination with the at least one pawl tooth hold the tongue in the locking head when pressure is applied to the tongue in the direction opposite to the direction of said insertion. This particular design of tie is preferred because the combined engagement of ratchet teeth on both sides of the tongue enhances the retaining function of the tie. Such a tie is described in United States Patents Nos. 4,473,524 to Paradis and 5,146,654 to Caveney et al.

[0002] Heretofore. it has not been considered practical to injection mold such a tie because it has been thought that such a tie could not be ejected from a mold following solidification of the tie without damage to the at least one stationary tooth unless the mold parts were separated at the portion of the mold cavity defining the apex of the at least one stationary tooth.

SUMMARY OF THE INVENTION

[0003] The present invention provides a method of injection molding a tie that is useful for forming a loop for retaining a bundle of elongated articles, the tie comprising an elongated tongue with two ends and two broad sides, a locking head at one end of the tongue, a tip at the other end of the tongue, a first set of ratchet teeth extending along one broad side of the tongue and a second set of ratchet teeth extending along the other broad side of the tongue, wherein the locking head has sides defining an opening for receiving the tip of the tongue, the sides including a movable pawl that is hinged at one side of said opening and an abutment surface that is on the other side of the opening from the pawl, wherein the pawl has at least one pawl tooth disposed for engaging the set of first ratchet teeth when the tip of the tongue has been inserted through said opening with the second set of ratchet teeth facing the abutment surface, wherein the pawl, when the at least one pawl tooth is so engaged, is movable toward the abutment surface in response to pressure applied to the tongue in a direction opposite to the direction of said insertion in order to force the second set of ratchet teeth against the abutment surface, and wherein at least one stationary tooth is disposed on the abutment surface and has an apex for engaging the second set of ratchet teeth when the second set of ratchet teeth is forced against he abutment surface to thereby in combination with the at least one pawl tooth hold the tongue in the locking head when pressure is applied to the tongue in the direction opposite to the direction of said insertion, the method comprising the steps of

(a) providing a mold by combining a first mold part defining a portion of a mold cavity that forms the first set of ratchet teeth on the one broad side of the tongue with a second mold part that defines a portion of the mold cavity that forms the second set of ratchet teeth on the other broad side of the tongue, wherein the second mold part includes a core that defines at least a portion of the mold cavity that forms the opening in the locking head;

(b) injecting molding material into the mold cavity to form the tie;

(c) solidifying the injected molding material to solidify the tie;

(d) opening the mold by separating the first mold part from the second mold parts; and,

(e) ejecting the solidified tie from the opened mold.
   characterized in that step (a) comprises combining the first mold part with the core of the second mold part at an interior parting surface that is remote from the portion of the mold cavity that forms the apex of the at least one stationary tooth;

step (d) comprises separating the first mold part from the second mold part at the interior parting surface; and,

step (e) comprises ejecting the solidified tie from the opened mold without the mold being opened at the portion of the mold cavity that forms the apex of the at least one stationary tooth.

[0004] Additional features of the present invention are described in relation to the detailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWING

[0005] Figure 1 is a top plan view of a tie that is injection molded in accordance with the present invention.

[0006] Figure 2 is a sectional view of the tie of Figure 1 taken along lines 2-2 in Figure 1.

[0007] Figure 3 is a plan view of the pawl of the tie of Figure 1 taken along lines 3-3 in Figure 2.

[0008] Figure 4 is a partial sectional view illustrating the ratchet teeth on opposite sides of the tongue of the tie of Figure 1 being engaged by the pawl teeth and the stationary teeth within the locking head.

[0009] Figure 5 is a partial sectional view of a portion of the mold that defines a portion of the mold cavity that forms the corresponding portion of the tie as taken along lines 5-5 in Figure 1.

DETAILED DESCRIPTION

[0010] Referring to the Drawing, a preferred embodiment of an injection molded tie 10 according to the present invention includes an elongated tongue 12. having two opposing broad sides 14, 16, a locking head 18 at one end of the tongue 12 and a tip 20 at the other end of the tongue 12. A first set of ratchet teeth 22 extends along one broad side 14 of the tongue 12 and a second set of ratchet teeth 24 extends along the other broad side 16 of the tongue 12. The first set of ratchet teeth 22 may be aligned with the second set of ratchet teeth 24 (not shown) or displaced from the second set of ratchet teeth 24, as shown in the Drawing. The distance by which the first set of ratchet teeth 22 is displaced from the second set of ratchet teeth 24 can be any percentage of the distance between adjacent ratchet teeth.

[0011] The locking head 18 has sides defining an opening 26 for receiving the tip 20 of the tongue 12 and thereby form a closed loop around a bundle of articles (not shown). The locking head 18 includes a movable pawl 28 that is hinged at one side of the opening 26 and has an abutment surface 30 on the opposite side of the opening 26 from the pawl 28. The abutment surface 30 is almost parallel to the surface 31 on the opposite side of the locking head wall containing the abutment surface 30.

[0012] The pawl 28 has two pawl teeth 32, 34 disposed for engaging the first set of ratchet teeth 22 when the tip 20 of the tongue 12 has been inserted through the opening 26 with the second set of ratchet teeth 24 facing the abutment surface 30. In other embodiments, the pawl 28 may have one or more than two pawl teeth.

[0013] One of the pawl teeth 34 includes a hollow section 36; and the opposite side of the pawl 28 includes a hollow section 38. These hollow sections 36, 38 are designed to prevent deformation of the pawl teeth 32, 34 during injection molding, as more fully described in applicants' copending U.S. Patent Applications Nos. 07/747,732 and 07/836,496. Such hollow sections 36, 38 are not required in all embodiments.

[0014] When the pawl teeth 32, 34 are engaged with the first set of ratchet teeth 22, the pawl 28 is movable toward the abutment surface 30 in response to pressure applied to the tongue 12 in a direction opposite to the direction of insertion 40 (Figure 4) in order to force the second set of ratchet teeth 24 against the abutment surface 30.

[0015] There are two stationary teeth 42 disposed on the abutment surface 30. Each stationary tooth 42 has a flat surface 44 terminating in an apex 46 for engaging the second set of ratchet teeth 24 in a portion of the tongue 12 engaged by the pawl teeth 32, 34 when the second set of ratchet teeth 24 is forced against the abutment surface 30 to thereby in combination with the two pawl teeth 32, 34 hold the tongue 12 in the locking head 18 when pressure is applied to the tongue 12 in the direction opposite to the direction of insertion 40. In other embodiments, there may be one or more than two stationary teeth 42 disposed on the abutment surface 30.

[0016] The positions of the pawl 28 and the abutment surface 30 can be interchanged to be on opposite sides of the opening 26 from the respective positions shown in the Drawing so that the abutment surface is on the side of the locking head 18 adjacent the tongue 12.

[0017] The tie 10 is injection molded by a method including the steps of

(a) providing a mold by combining mold parts 50, 52 (Figure 5) to define a mold cavity 54 for forming the tie 10;

(b) injecting molding material into the mold cavity 54 to form the tie 10;

(c) solidifying the injected molding material to solidify the tie 10;

(d) separating the mold parts 50, 52 to open the mold; and

(e) ejecting the solidified tie 10 from the opened mold.

[0018] Step (a) includes providing a first mold part 50 defining a portion of the mold cavity 54 that forms the first set of ratchet teeth 22 on the one broad side 14 of the tongue 12 and a second mold part 52 opposing the first mold part 50 that defines a portion of the mold cavity 54 that forms the second set of ratchet teeth 24 on the other broad side 16 of the tongue 12. The second mold part 52 includes a core 56 that defines at least a portion of the mold cavity 54 that forms the opening 26 in the locking head 18. The first mold part 50 is combined with the core 56 of the second mold part 52 at an interior parting surface 58 that is remote from the portions 60 of the mold cavity 54 that form the apexes 46 of the two stationary teeth 42. An exterior parting surface 62 circumscribes the mold cavity 54 and is approximately coplanar with the interior parting surface 58. In other embodiments, an exterior parting surface circumscribing the mold cavity 54 need not be coplanar with the interior parting surface 58. A parting surface is a surface which when the mold is closed contacts the opposing mold part and which when the mold is opened is separated from the opposing mold part.

[0019] Steps (d) and (e) include ejecting the solidified tie 10 from the opened mold without separating the mold parts 50. 52 at any portion of the mold cavity that forms either of the two stationary teeth apexes 46.

[0020] The tie 10 is molded from Nylon 6.6 molding material with steel mold parts 50, 52 that are cooled to within a temperature range of approximately 10 to 20 degrees Centigrade. The method is operable at other temperatures.

[0021] When the mold is opened, the tie 10 is ejected by an ejector (not shown) at an ejection speed of 200 millimeters per second. The method is operable at other ejection speeds.

[0022] The method of the present invention can be used to simultaneously injection mold a plurality of ties 10 with a mold defining a plurality of mold cavities 54 for forming the plurality of ties.

Claims

1. A method of injection molding a tie (10) that is useful for forming a loop for retaining a bundle of elongated articles, the tie comprising an elongated tongue (12) with two ends and two broad sides (14, 16), a locking head (18) at one end of the tongue, a tip (20) at the other end of the tongue, a first set of ratchet teeth (22) extending along one broad side of the tongue and a second set of ratchet teeth (24) extending along the other broad side of the tongue, wherein the locking head has sides defining an opening (26) for receiving the tip of the tongue, the sides including a movable pawl (28) that is hinged at one side of said opening and an abutment surface (30) that is on the other side of the opening from the pawl, wherein the pawl has at least one pawl tooth (32, 34) disposed for engaging the set of first ratchet teeth when the tip of the tongue has been inserted through said opening with the second set of ratchet teeth facing the abutment surface, wherein the pawl, when the at least one pawl tooth is so engaged, is movable toward the abutment surface in response to pressure applied to the tongue in a direction opposite to the direction of said insertion (40) in order to force the second set of ratchet teeth against the abutment surface, and wherein at least one stationary tooth (42) is disposed on the abutment surface (30) and has an apex (46) for engaging the second set of ratchet teeth (2) when the second set of ratchet teeth is forced against the abutment surface to thereby in combination with the at least one pawl tooth (32, 34) hold the tongue in the locking head (18) when pressure is applied to the tongue (12) in the direction opposite to the direction of said insertion (40), the method comprising the steps of

(a) providing a mold by combining a first mold part (50) defining a portion of a mold cavity (54) that forms the first set of ratchet teeth (22) on the one broad side of the tongue (12) with a second mold part (52) that defines a portion of the mold cavity that forms the second set of ratchet teeth (24) on the other broad side of the tongue, wherein the second mold part includes a core (56) that defines at least a portion of the mold cavity that forms the opening (26) in the locking head (18);

(b) injecting molding material into the mold cavity to form the tie;

(c) solidifying the injected molding material to solidify the tie;

(d) opening the mold by separating the first mold part from the second mold parts; and

(e) ejecting the solidified tie from the opened mold;
   characterised in that step (a) comprises combining the first mold part with the core of the second mold part at an interior parting surface (58) that is remote from the portion (60) of the mold cavity that forms the apex (46) of the at least one stationary tooth (42);

step (d) comprises separating the first mold part from the second mold part at the interior parting surface (58); and

step (e) comprises ejecting the solidified tie from the opened mold without the mold being opened at the portion (60) of the mold cavity that forms the apex (46) of the at least one stationary tooth (42).

2. A method according to Claim 1, characterised in that step (a) further comprises combining the first mold part (50) with the second mold part (52) at a said interior parting surface (58) that lies in approximately a single plane and at an exterior parting surface (62) that circumscribes the mold cavity and is approximately coplanar with the interior parting surface.

3. A method according to Claim 1 or 2, wherein at least two said stationary teeth (42) respectively having apexes (46) are disposed on the abutment surface (30) for engaging different teeth of the second set of ratchet teeth when the second set of ratchet teeth is so forced against the abutment surface,
   characterised in that step (a) comprises combining the first mold part with the core of the second mold part at an interior parting surface (58) that is remote from the apexes of the at least two stationary teeth; and
   step (e) comprises ejecting the solidified tie from the opened mold without the mold being opened at at least one portion (60) of the mold cavity that forms the apex (46) of one of the at least two stationary teeth.

4. A method according to Claim 1, 2 or 3, wherein the paw] has at least two teeth (32, 34) disposed for engaging different teeth of the first set of ratchet teeth (22) when the tip (20) of the tongue (12) is so inserted through said opening (26).

5. A method according to Claim 1, for simultaneously injection molding a plurality of ties with a mold defining a plurality of said mold cavities (54) for forming said plurality of ties.

Ansprüche

1. Verfahren zum Spritzgießen eines zur Bildung einer Schlaufe zum Halten eines Bündels von langestreckten Gegenständen einsetzbaren Binders (10) mit einer langestreckten Zunge (12) mit zwei Enden und zwei breiten Seiten (14,16), mit einem Arretierkopf (18) an einem Ende der Zunge, mit einer Spitze (20) am anderen Ende der Zunge, mit einem ersten Satz von Rastzähnen (22), die sich längs einer breiten Seite der Zunge erstrecken, und mit einem zweiten Satz von Rastzähnen (24), die sich längs der anderen breiten Seite der Zunge erstrecken,

- wobei der Arretierkopf eine Öffnung (26) für die Aufnahme der Spitze der Zunge begrenzende Seiten hat,

- wobei die Seiten ein an einer Seite der Öffnung angelenktes bewegliches Klinkelement (28) und auf der von dem Klinkelement aus anderen Seite der Öffnung eine Widerlagerfläche (30) aufweisen,

- wobei das Klinkelement wenigstens einen Klinkzahn (32,34) hat, der für einen Eingriff mit dem Satz von ersten Rastzähnen angeordnet ist, wenn die Spitze der Zunge durch die Öffnung hindurch so eingeführt worden ist, daß der zweite Satz von Rastzähnen der Widerlagerfläche zugewandt ist,

- wobei das Klinkelement, wenn der wenigstens eine Klinkzahn so in Eingriff gebracht ist, zu der Widerlagerfläche ansprechend auf einen Druck bewegbar ist, der auf die Zunge in eine Richtung entgegengesetzt zur Einführrichtung (40) ausgeübt wird, um den zweiten Satz von Rastzähnen gegen die Widerlagerfläche zu drücken, und

- wobei wengistens ein stationärer Zahn (42) an der Widerlagerfläche (30) angeordnet ist und einen Scheitel (46) für den Eingriff mit dem zweiten Satz von Rastzähnen (2) hat, wenn der zweite Satz von Rastzähnen gegen die Widerlagerfläche gedrückt wird, um dadurch in Kombination mit dem wenigstens einen Klinkzahn (32,34) die Zunge in dem Arretierkopf (18) zu halten, wenn Druck auf die Zunge (12) in die zur Einführrichtung (40) entgegengesetzten Richtung ausgeübt wird,

- wobei das Verfahren die Schritte aufweist,

a) Bereitstellen einer Form durch Kombinieren eines ersten Formteils (50), das einen Abschnitt eines Formhohlraums (54) begrenzt, der den ersten Satz von Rastzähnen (22) an der einen breiten Seite der Zunge (12) formt, mit einem zweiten Formteil (52) welches einen Abschnitt des Formhohlraums begrenzt, der den zweiten Satz von Rastzähnen (24) auf der anderen breiten Seite der Zunge formt, wobei das zweite Formteil einen Kern (56) hat, der wenigstens einen Abschnitt des Formhohlraums begrenzt, der die Öffnung

(26) in dem Arretierkopf (18) bildet, b) Spritzgießen von Material in den Formhohlraum zur Formung des Binders,

c) Verfestigen des Spritzgießmaterials zur Verfestigung des Binders,

d) Öffnen der Form durch Trennen des ersten Formteils von dem zweiten Formteil und

e) Auswerfen des verfestigten Binders aus der geöffneten Form,

dadurch gekennzeichnet,

- daß Schritt a) das Kombinieren des ersten Formteils mit dem Kern des zweiten Formteils an einer inneren Trennfläche (58) aufweist, die von dem Abschnitt (60) des Formhohlraums entfernt liegt, der den Scheitel (46) des wenigstens einen stationären Zahns (42) formt,

- daß Schritt d) das Trennen des ersten Formteils von dem zweiten Formteil an der inneren Trennfläche (58) aufweist und

- daß Schritt e) das Auswerfen des verfestigten Binders aus der geöffneten Form aufweist, ohne daß die Form an dem Abschitt (60) des Formhohlraums geöffnet wird, der den Scheitel (46) des wenigstens einen stationären Zahns (42) formt.

2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß Schritt a) weiterhin das Kombinieren des ersten Formteils (50) mit dem zweiten Formteil (52) an der inneren Trennfläche (58) aufweist, die in annähernd einer einzigen Ebene und an einer äußeren Trennfläche (62) liegt, welche den Formhohlraum umschreibt und annähernd koplanar zu der inneren Trennfläche ist.

3. Verfahren nach Anspruch 1 oder 2, bei welchem wenigstens zwei stationäre Zähne (42), welche jeweils Scheitel (46) haben, an der Widerlagerfläche (30) für den Eingriff mit unterschiedlichen Zähnen des zweiten Satzes von Rastzähnen angeordnet sind, wenn der zweite Satz von Rastzähnen so gegen die Widerlagerfläche gedrückt wird,
dadurch gekennzeichnet,

- daß Schritt a) das Kombinieren des ersten Formteils mit dem Kern des zweiten Formteils an einer inneren Trennfläche (58) aufweist, die von den Scheiteln der wenigstens zwei stationären Zähen entfernt ist, und

- daß Schritt e) das Auswerfen des verfestigten Binders aus der geöffneten Form aufweist, ohne daß die Form an wenigstens einem Abschitt (60) des Formhohlraums geöffnet wird, der den Scheitel (46) eines der wenigstens zwei stationären Zähne (42) formt.

4. Verfahren nach Anspruch 1, 2 oder 3, bei welchem das Klinkelement wenigstens zwei Zähne (32,34) hat, die für einen Eingriff mit unterschiedlichen Zähnen des ersten Satzes von Rastzähnen (22) angeordnet sind, wenn die Spitze (20) der Zunge (12) so durch die Öffnung (26) eingeführt wird.

5. Verfahren nach Anspruch 1, zum gleichzeitigen Spritzgießen einer Vielzahl von Bindern mit einer Form, welche eine Vielzahl der genannten Formhohlräume (54) zum Formen der Vielzahl von Bindern enthält.

Revendications

1. Procédé pour le moulage par injection d'un collier (10) servant à former une boucle pour maintenir en place un faisceau de produits oblongs, le collier comprenant une languette oblongue (12) avec deux extrémités et deux côtés larges (14, 16), une tête de blocage (18) sur une extrémité de la languette, une pointe (20) sur l'autre extrémité de la languette, une première série de dents à cliquet (22) s'étendant le long d'un côté large de la languette, et une seconde série de dents à cliquet (24) s'étendant le long de l'autre côté large de la languette, la tête de blocage présentant des côtés définissant une ouverture (26) pour recevoir la pointe de la languette, les côtés incorporant un cliquet mobile (28) qui est articulé sur un côté de l'ouverture et une surface de butée (30) qui se situe sur l'autre côté de l'ouverture en partant du cliquet, le cliquet présentant au moins une dent de cliquet (32, 34) disposée pour l'engagement de la série des premières dents à rochet lorsque la pointe de la languette a été introduite à travers l'ouverture avec la seconde série de dents à rochet en regard de la surface de butée, lorsqu'au moins une dent de cliquet est engagée, le cliquet pouvant se déplacer vers la surface de butée en réponse à une pression appliquée sur la languette dans une direction opposée à la direction de l'insertion (40) pour forcer la seconde série de dents à rochet contre la surface de butée et au moins une dent fixe (42) étant disposée sur la surface de butée (30) avec un sommet (46) pour l'engagement de la seconde série de dents à rochet (2) lorsque la seconde série de dents à rochet est forcée contre la surface de butée afin de maintenir en combinaison avec au moins une dent de cliquet (32, 34) la languette dans la tête de blocage (18) lorsque la pression est appliquée sur la languette (12) dans la direction opposée à la direction de l'introduction (40), le procédé comprenant les étapes consistant à :

(a) mettre en place un moule en combinaison à une première partie de moule (50) définissant une portion de cavité de moule (54) qui forme la première série de dents de rochet (22) sur le côté large de la languette (12) avec une seconde partie de moule (52) qui définit une portion de la cavité de moule qui forme la seconde série de dents à rochet (24) sur l'autre côté large de la languette, la seconde partie de moule incorporant un noyau (56) qui définit au moins une portion de la cavité de moule qui forme l'ouverture (26) dans la tête de blocage (18);

(b) injecter le matériau de moulage dans la cavité de moule pour former le collier ;

(c) solidifier le matériau de moulage injecté pour solidifier le collier ;

(d) ouvrir le moule en séparant la première partie de moule des secondes parties de moule ; et

(e) éjecter le collier solidifié du moule ouvert ;
   caractérisé en ce que l'étape (a) comprend l'opération consistant à combiner la première partie de moule avec le noyau de la seconde partie de moule au niveau d'une surface de séparation intérieure (58) qui est éloignée de la portion (60) de la cavité de moule qui forme le sommet (46) d'au moins une dent fixe (42) ;

l'étape (d) comprend la séparation de la première partie de moule de la seconde partie de moule au niveau de la surface de séparation intérieure (58) ; et

l'étape (e) comprend l'éjection du collier solidifié du moule ouvert sans ouvrir le moule au niveau de la portion (60) de la cavité de moule qui forme le sommet (46) d'au moins une dent fixe (42).

2. Procédé selon la revendication 1, caractérisé en ce que l'étape (a) comprend de plus l'opération consistant à combiner la première partie de moule (50) avec la seconde partie de moule (52) au niveau de la surface de séparation intérieure (58) qui se situe approximativement dans un seul plan et au niveau d'une surface de séparation extérieure (62) qui circonscrit la cavité de moule et qui est approximativement située dans le même plan que la surface de séparation intérieure.

3. Procédé selon la revendication 1 ou 2, dans lequel au moins deux dents fixes (42) avec respectivement des sommets (46) sont disposées sur la surface de butée (30) pour l'engagement de différentes dents de la seconde série de dents à rochet lorsque la seconde série de dents à rochet est forcée contre la surface de butée,
   caractérisé en ce que l'étape (a) comprend l'opération consistant à combiner la première partie de moule avec le noyau de la seconde partie de moule au niveau de la surface de séparation intérieure (58) qui est éloignée des sommets d'au moins deux dents fixes ; et
   l'étape (e) comprend l'éjection du collier solidifié à partir du moule ouvert sans ouvrir le moule au niveau d'au moins une portion (60) de la cavité de moule qui forme le sommet (46) d'au moins deux dents fixes.

4. Procédé selon la revendication 1, 2 ou 3, dans lequel le cliquet comporte au moins deux dents (32, 34) disposées pour l'engagement de différentes dents de la première série de dents à rochet (22) lorsque la pointe (20) de la dent (12) est introduite à travers l'ouverture (26).

5. Procédé selon la revendication 1, pour le moulage par injection simultanément d'une pluralité de colliers avec un moule définissant une pluralité de cavités de moule (54) pour former la pluralité de colliers.

Drawing